1. Field of the Invention
The present invention relates to an optical signal transmission substrate which uses optical signals as input and output information. More particularly, this invention relates to a substrate appropriate for high-density packaging of, for example, electronic computers, and also relates to an optical signal transmission device which utilizes such substrate.
2. Description of the Related Art
Regarding conventional devices such as electronic computers, a plurality of substrates necessary to compose circuits are mutually connected through electrical wiring by using conductive lines such as cables or wires. Signals sent and received between the substrates are electric signals which generate interface elements.
With some devices, such optical signal transmission is realized as a light emitting element is provided on one substrate and a light receiving element is provided on the other substrate, thereby connecting both elements with optical fibers.
Since the connection using conductive lines causes a signal delay due to the existence of the capacity for wiring and the wiring resistance, it is not suited for the wiring between substrates of high-speed and high-density packaging devices. There is another inconvenience of generating heat due to the wiring resistance.
On the other hand, the connection utilizing optical fibers requires a large number of optical fibers for multiple wiring such as buses and also requires enormous man-hours for the wiring work, and the increase in costs required for the wiring is inevitable.